Anaesthetics: inexperienced personnel found laryngeal tubes easier and faster to insert than endotracheal tubes

Clinical bottom line (level 2b)

  1. Insertion of laryngeal masks by inexperienced personnel was more likely to be successful than intubation with endotracheal tubes (NNT = 3 at minutes) and faster (on average by 15 seconds).
Davies et al: Lancet 1990; 336: 977-979
Expires October 2003

The study

Single-blinded ?concealed quasi-randomised trial with intention-to-treat
Setting: military hospital, UK

110 patients (aged , % male) undergoing routine elective surgery

Excluded if
  • unfit for either endotracheal intubation or laryngeal mask
  • loose teeth or crowns
  • ASA 2 or worse


    • Note:
  • All patients had one tube inserted, then removed, followed by insertion of the other tube.


    • Control Group: (n = , analysed): endotracheal tube
    Experimental Group: (n = , analysed): laryngeal mask
    Intubations were performed by 11 Royal Navy medical trainees with no previous experience except manikin practice.
    100% followed for ?
    Outcome notes:
    • successful "intubation" : production of carbon dioxide within 40 seconds of Guedel airway removal, which rose to at least 4.0 kPa , together with satisfactory lung expansion and ventilation

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    successful "intubation" unknown 56
    (50.9%)    		 103
    (93.6%)    		 84%
    (67% to 34%)    		 34.55%
    (24.29% to 44.8%)    		 3
    (2 to 4)

    Comments

    1. Mean insertion time for laryngeal masks was 20 seconds, and 35 seconds for ET tubes (mean difference 15 seconds; p< 0.01)
    2. Timings likely to be overestimates for emergency situations as controlled environment and 'good' patients (i.e. ASA I)

    Citation

    1. Davies PR, Tighe SQ, Greenslade GL, et al: Laryngeal mask airway and tracheal tube insertion by unskilled personnel. Lancet 1990; 336: 977-979
    Contributor: Chris Ball and Musab Hayatli, October 1999
    Reviewer: Graham Cooke

    Clinical Question.
    Patient elective surgery
    Intervention or Exposure laryngeal mask
    Comparison endotracheal tube
    Outcome successful intubation, speed of intubation